1. Field of the Invention
The invention relates to an optical scanner of a facsimile, a copying machine and other machines provided with an image reading function for reading the image of an object by optically scanning the object to be read.
2. Description of Related Art
Heretofore, in an image reader of, for example, a copying machine for outputting a monochrome or multiple-color printed copy, a light beam from a light source with a single wavelength or a plurality of different wavelengths is radiated on the object, such as an original to be printed, to be read by scanning deflection using a rotating polygon mirror, a galvanomirror, a hologram disc using diffraction effect, a solid deflecting element for deflecting light by varying a refraction index in an optical waveguide acousto-optically or magneto-optically and other comparable devices. The reflected light from the object is received by a light receiving element, such as a photodiode (PD), and image information corresponding to the object read is obtained based upon a signal from the light receiving element.
However, in the above conventional type copying machine, as the reflected light is received by a plurality of light receiving means to obtain image information corresponding to the object, such as disclosed in U.S. Pat. Application No. 08/617,057, for example, the signal waveforms are not uniform when the signals are simultaneously obtained from different light receiving means. Thus, a ripple is caused and the quality of the signals deteriorates. Particularly, when signal variation, in a state in which reflected light transits from one detector to the next detector, is abrupt (i.e. overlap is small), as shown in FIGS. 11 and 12, and a focusing detecting lens is arranged in the light receiving means to improve the quality of a signal, a large ripple is caused in a signal waveform in an area in which signals of the light receiving means are overlapped and correction is difficult.